Field of the Invention
The present invention relates to a chip spacing maintaining apparatus for maintaining the spacing between chips formed by expanding an expand sheet.
Description of the Related Art
In compact and lightweight electronic equipment represented by a mobile phone, a device chip having a device such as an IC is an essential component. Such a device chip (which will be hereinafter referred to simply as chip) is manufactured by using wafer formed of silicon, for example, partitioning the front side of the wafer with a plurality of division lines called streets to thereby form a plurality of separate regions, forming a device in each separate region, and dividing the wafer along each street.
In recent years, there has been put into practical use a dividing method including the steps of forming a modified layer as a division start point inside the wafer along each street and next applying an external force to the wafer, thereby dividing the wafer along each street to obtain a plurality of chips (see Japanese Patent Laid-Open No. 2011-77482, for example). In this dividing method, an expand sheet is attached to the wafer in which the modified layer is formed, and the expand sheet is expanded to thereby apply an external force to the wafer.
To maintain the spacing between the chips formed by expanding the expand sheet, there has been proposed a method including the step of heating the expand sheet in the area between the outer circumference of the wafer and the inner circumference of an annular frame fixed to the peripheral portion of the expand sheet, thereby partially shrinking the expand sheet expanded in this area (see Japanese Patent Laid-Open No. 2012-156400, for example). Accordingly, the increased spacing between the chips can be maintained by this method to thereby facilitate a subsequent handling operation or the like.